Species: Canine | Classification: Techniques
- Injection of positive contrast into circulation allows visualization of vascular system.
- Investigation of:
- Assessment of perfusion.
- Relatively simple procedure.
- Equipment available in general practice.
- Good anatomical detail.
- General anesthesia often required (and patient may be severely compromised).
- Fluoroscopy required for selective angiography.
- Scintigraphy (allows assessment of vascular perfusion and ventilation perfusion ratio).
- Ultrasonography for measurement of cardiac chamber size, presence of vascular shunts and thrombotic disease.
- Fluoroscopy gives better visualization of dynamic lesions.
- 15 min.
- 10 min.
Criteria for choosing test
- Is the examination appropriate?
- Can you make the diagnosis without it?
- Will your management of the case be affected by the outcome of the examination?
- For many conditions where vascular contrast studies are indicated the patient is likely to be clinically ill, eg pulmonary thromboembolism, therefore careful assessment of risks of anesthesia/sedation should be made.
- X-ray machine that allows rapid multiple exposures to be made.
- Processing facilities.
- Protective clothing (lead apron) for radiographer.
- Positioning aids (sandbags, cradle and ties).
- Method of labelling film.
- Cassette tunnel.
- Rapid cassette changer to allow multiple exposures to be made.
- Ability to process films during procedure so that repeat radiographs can be taken during course of study if required.
- High output X-ray machine.
- High definition screen.
- Grid for examination of large dog.
- Radiographic film.
- Intravenous catheter (large bore; 20G).
- Contrast agent (water-soluble, iodine-based).
- Ideally non-ionic, low osmolar water-soluble contrast is used, eg iohexol as this is less likely to cause circulatory disturbances.
- General anesthesia.
- Pre-place catheter in peripheral vein (for non-selective angiography), usually jugular or cephalic Cephalic catheterization.
- Catheterization of specific region requires more experience and may need fluoroscopic guidance.
Step 1 - Control Films
- Check exposure settings and processing.
- Confirm positioning adequate.
- Confirm diagnosis not apparent without contrast study.
Step 1 - Non-selective angiography
- Inject contrast agent 200 mg iodine/0.45 kg as rapidly as possible.
In large dogs injection via the jugular is preferable to permit rapid infusion of large volumes required.
Step 2 - Selective angiography
- Introduce bolus of contrast agent at specific site, eg cardiac chamber, renal artery.
Fluoroscopy may be required to ensure catheter in correct site at time of injection.
Step 3 - Make exposure
- Make exposure immediately after injection.
- Exposure multiple films in rapid succession.
Step 1 - Assess radiographs
- Has structure of interest been exposed during time of contrast presence?
- If not, repeat films after second contrast injection.
- Recent references from PubMed and VetMedResource.
- Wise M (1982) Non-selective angiocardiography in the normal dog and cat. Vet Radiol 23 (4), 144-151 VetMedResource.
Other sources of information
- Fox P R & Bond B R (1983) Non-selective and selective angiocardiography. Vet Clin North Am Small Anim Pract 13 (2), 259-272 PubMed.